Scientists have implanted a chip inside the brains of rhesus monkeys and seen their decision making and thinking improve. The breakthrough is an important step on what will be a long road to bringing brain prostheses to stroke victims and those suffering from dementia and brain injuries.

Previous research showed that a neural implant could boost memory in rodents, but this demonstration of a device that could enhance fairly advanced mental skills was the first in primates, whose brains are more similar to those in humans.

Published in the Journal of Neural Engineering, the paper, by researchers at Wake Forest Baptist Medical Center and the University of Southern California, also builds upon previous brain implants that improved the brain's ability to do physical things such as see better, control prosthetic limbs or move computer cursors. What sets this device apart is that it improves the brain's internal function.

The experiments

The study began with the researchers teaching five rhesus monkeys to play a picture-matching game. They would be shown an image, such as of a toy, mountains or a person, and then later on, they'd have to select the matching image from a group of them. Every time they guessed correctly, they got a treat.

The monkeys improved over two years of playing the game -- getting 75% of the easy matches correct and 40% of the harder ones, which is better than chance guessing.

Then, the monkeys got a tiny brain implant with two sensors that was threaded through the forehead and into two nearby layers of the cerebral cortex, which is the outer covering of the brain. The two layers are known to communicate with each other during the type of decision making in which the monkeys engaged while playing the picture-matching game.

The implant logged how the neurons were firing while the animals were making their choices and sent the data to a computer. The researchers then found the pattern that occurred when the monkeys chose the correct images.

Then, the scientists put this "correct" pattern into the monkeys' brains while they were in the middle of choosing the matching picture; doing so improved their performance by about 10%.

The scientists tested it again by purposely impairing the monkeys' performance by giving them cocaine, which caused their scores to drop by 20%.

But, with the stimulator on, they didn't make mistakes.

Applications

While the commercial version of this device is years away, co-author Sam A. Deadwyler a Wake Forest University told The New York Times, “The whole idea is that the device would generate an output pattern that bypasses the damaged area, providing an alternative connection” in the brain.

But the road to such a device could be long given that decision making is a complex process involving many neural circuits.

The Times concludes:

"A device focused on just one circuit is likely to be very limited. But not long ago, even a simple neural prosthesis would have seemed like science fiction."